I have a PFD for my cat and it seems to be fairly stable, although to be fair, she hasn't had occasion to try to seriously escape (a piteous "mew" is enough to make me relent, remove it, and soothe a ruffled ego). The best part, though, it that it has a handle. She looks a bit bewildered and is strangely calm when I carry her like a briefcase.
More seriously, the biggest issue (for me, anyway) with taking a cat cruising is her wandering off... even though she has done about 25,000 miles with me on land. There are disturbing tales of kitties exploring the marina, finding an intriguing open hatch
with interesting galley
smells, and jumping onto a V-berth somewhere... only to have no way out. My solution to all this is a light-weight harness with a bit of electronics
: a remotely actuated blinking LED and beeper along with a simple RF beacon (not GPS
, just a homing signal... tiny and lightweight, though a bit challenging to track). I've played with getting her to haul around a wireless video camera
, but the range is too short to be practical and they gobble too much power.
(The beacon is surprisingly easy - just a crystal oscillator worth a couple of bucks and a quarter-wave dipole antenna
threaded through the harness. The circuit power-cycles it at 2 Hz to make a recognizable signal, and standard ham-radio "fox hunting" techniques are used to home in. Good for a mile or so on land, and very low current
drain. A better solution would be one of the systems they sell for falconry, with a hand-held folding yagi antenna
... but they are EXPENSIVE.)
The remote-actuation bit is easy with some of the RF modules from sparkfun.com (no relation, just a happy customer of their varied gizmology).
Steve (and Java-the-cat)